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Introduction to statistics

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Introduction to statistics

  3. 3. SINGULAR SENSE “Statistics is the collection, classification, analysis and presentation of numerical data” -CROXTON AND COWDEN PLURAL SENSE “Statistics are numerical statements of facts in any department of enquiry placed in relation to each other” -BOWLEY
  4. 4. Statistics means the various methods adopted for the collection, analysis and interpretation of the figures. Further, in singular sense ,The concept of statistics is described as statistical methods. The Statistical method is “A Telescope through which we can study a large terrain that would be accessible to our unaided Vision”.Thus it may be stated that statistics is a science of collection, presentation, analysis, and interpretation of data.
  5. 5. It means a collection of numerical facts. It is in this sense that the public usually think of statistics as figures concerned with population or production of wheat in different years or number of man-hours lost in specific year. Secondary Statistics eg- percentages, averages and coefficients derived from numerical facts, are also included in the term “Statistics” in this sense.
  6. 6. • Aggregates of Facts: Single height 5’6 or 6’0 is not statistics but a series relating to the height of a group of persons is called statistics. • Affected by multiplicity of causes: Statistics are affected by large number of factors. Ex: Prices are affected by conditions of demand, supply, money supply, imports, exports etc. • Numerically Expressed: Qualitative expressions like young, old, good, bad, etc are not recognized. so, a numerical value like 932 females per 1000 males in India and 1170 females per 1000 males in USSR.
  7. 7. • Collected in a systematic Manner-For Accuracy and reliability of data, the figures should be collected in a systematic manner. • Collected for pre-determined purpose-Data should be collected with some pre determined purpose. Figures should be collected with some objective in we want collect data on prices, then we must be clear whether we have to collect wholesale or retail prices. • Placed In relation to each other-collection of data is done with a motive to compare. Figures collected should be comparable Eg-It does not make any sense if we compare height of a person and rent he pays for his accommodation.
  8. 8. • Collection of Data- It is the first step in statistical enquiry. The technique depends upon the objective of the study. They should be collected carefully so as to fulfill the basic objective of the purposed study. • Organization of Data- After collection, the data are organised in a proper form which involves editing(removing errors),classification(arranging) and tabulation(columns and rows).
  9. 9. • Presentation of Data-Now the data is presented in a suitable manner- either by diagrams or graphs. • Analysis of Data- Analysis follows the presentation of data. simple mathematical techniques are applied in analysis. These include central tendency, measures of dispersion, correlation and regression etc. The main purpose of analysis is to draw some meaningful conclusions. •Interpretation- It is the last step in the statistical methodology. To derive meaning from analysed data is called interpretation of data. It involves statistical thinking, skill and experience. It provides final conclusions.
  11. 11. Descriptive Statistics: It deals with methods which help in estimating the characteristics of a population or making decisions concerning a population on the basis of the sample results. Sample and population are the two relative terms. A Population is treated as universe and a sample is fraction or segment of the universe.
  12. 12. It means to describe the data and consists of the methods and techniques used in the collection, organisation, presentation and analysis of data in order to describe the various features and characteristics of such data. These can either be graphical or computational. In this, nothing can be inferred from the data nor can decision be made or conclusion drawn.
  13. 13. The nature of statistics is to find out whether it is a science or Art. As a science, Statistics studies numerical data in a systematic manner and as an art, it makes use of the data to solve the problems of real life.
  14. 14.  Expression of Facts in Numbers  Simple Presentation  Enlarges Individual Knowledge and Experience  It Compares Facts  It Facilitates Policy Formulation  It Helps Other Sciences in Testing their Laws  It Establishes Relationship between Facts- Statistics also establishes relationship between two or more than two facts.  Enlarges individual Knowledge & Experience.
  15. 15.  Administrators  Economist  Buisness,Industry &Agriculture  Politicians  Social Reformer  Science & Research  Insurance Companies  Education
  16. 16.  Study of Numerical facts only.  Study of Aggregates only.  Not the only Method.  Homogeneity of Data.  Results are true only on an Average.  Without reference result may prove wrong.  Can be Used only by Experts.  Misuse of Statistics is possible.